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CYWD 2007 QAQC Results: Preliminary Data Analysis and Crew Comparison

This report presents the preliminary data analysis results from the 2007 Conservation Halton QAQC project. The analysis includes comparison based on the best measure of discharge and variance between different crew types. Findings reveal agreement levels and discrepancies among volunteer, QAQC, and agency crews for various methods. Recommendations address issues related to measurement accuracy and crew performance. Overall, the study emphasizes the importance of method accuracy and consistency in flow measurement practices for future QAQC initiatives.

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CYWD 2007 QAQC Results: Preliminary Data Analysis and Crew Comparison

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  1. CYWD 2007 QAQC Results Sarah Hogg Conservation Halton

  2. Preliminary Data Analysis • 431 sites observed total • 115 QAQC sites total • 26.6 % QAQC sites • Percent agreement on perched versus non-perched culverts = 94.3% (agency staff issue) • Percent agreement wet versus dry streams = 100%

  3. Data Analysis Overview • Identified 3 different crew types on CYWD: Volunteer Crew, Volunteer QAQC Crew, Agency Crew • Hierarchy of methods used on day: Volume/Time, HH, Distance/Time • Final Q value for each site determined based on discharge value observed by agency staff using best available method • Analyzed data based on: 1.) Comparison based on best measure of discharge 2.) Variance between crews using the same method

  4. Comparison Based on Best Measure of Discharge • Relatively few observation points for each method • Standard deviation values high in comparison to discharge values observed • Negative slopes observed are attributed to methods where variance and measurability decrease as velocity increases • One agency HH measurement omitted from analysis (obvious outlier) • Agency Vol/Time was value used for most Final Q values

  5. Method Comparison by Crew Type • Similar slope observed by all crews types for most methods • Bias obvious for some methods (ie: HH) • Slope of volunteer QAQC line is always closer to agency than individual volunteer

  6. Comparison Between Crews Using Same Method • Relatively few observation points • Standard deviation between crews relatively low • Negative slopes observed for methods where variance increases with increased flow (Volume/Time and HH)

  7. Comparison Between Crews Using Same Method • Good agreement for the HH measures • Some evidence that the QAQC crew was more similar to the agency crew than the average volunteer

  8. Conclusions/Recommendations • Scale issue (confidence intervals for methods not known) • Measures of HH seem to be done quite well, exception is when HH is low (>2) • Distance/Time and Volume/Time methods not as repeatable

  9. Conclusions/Recommendations (cont’d) Recommendations: • Low hydraulic head is low (>2mm) use distance/time, when and where appropriate • More emphasis should be placed on accuracy of float and volume by time • Go downstream to measure flow! • Next Step – write up

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